The present invention generally relates to wound dressings and, more particularly, to a wound dressing in the form of gauze or similar absorbent material having a dehydrated hydrogel material impregnated therein for absorbing wound exudate and which further includes an additional absorbent layer for absorbing exudate passed through or not absorbed by the absorbent material and dehydrated hydrogel.
Secreting skin wounds, such as decubitus ulcers and open surgical wounds, have long presented a medical challenge in keeping such wounds sterile and relatively dry. The accumulation of wound exudate, such as blood, pustulation, and other wound fluids, in wound crevices, promotes growth of bacteria and crusted organisms which cause infection and delay the healing process. Such wound exudate may also cause maceration of tissue adjacent the wound and support infection thereof. However, since it is often desirable to allow a wound to heal in a slightly "moist" or occlusive state, which is believed to accelerate healing, excess wound exudate must be removed. If excess wound exudate remains on a wound, a "blister" of exudate can form under the wound dressing which is not only unsightly, but also may cause the dressing to leak, thereby defeating the aim of sterility. However, existing methods of aspiration can lead to wound infection or can destroy sterility. Additionally, it is not desirable to remove all the exudate as that: would result in a "dry" wound resulting in a slower healing process.
The art is replete with wound and/or surgical dressings for treating skin lesions, such as decubitus ulcers and open surgical wounds. For example, Mason, Jr. et al, U.S. Pat. No. 4,393,048, disclose a hydrogel wound treatment composition which dries to a powder after it is introduced into an open, draining wound to absorb wound exudate. However, dry hydrogel deteriorates as the wound fluids are absorbed resulting in lumping and uneven application. Additionally, such deteriorated lumps are difficult to remove from a wound site without damaging new cell tissue at the wound site. Furthermore, the progress of wound healing cannot be determined without removing, at least partially, the wound dressing from the wound site.
Aqueous moisture absorbing materials, such as a hydrogel material with a polyethylene glycol liquid curing agent as disclosed in Spence, U.S. Pat. No. 4,226,232, are easier to remove from the wound site, but cannot be sterilized by irradiation due to the formation of free radicals within the aqueous material. Another aqueous absorbing material used to absorb wound exudate is a hydrophilic polymer as disclosed in Rawlings et al, U.S. Pat. No. 4,657,006. Rawlings et al disclose a wound dressing which comprises a hydrophilic polymer having moisture and vapor permeability characteristics. However, a problem with the Rawlings et al wound dressing is that the wound exudate absorbed by the hydrophilic polymer hardens or solidifies the polymer, allowing pockets to develop between the polymer and the wound, thereby providing an excellent environment for bacteria proliferation.
In addition, wound dressings used in the past have not been conducive for healing extremely deep wounds and wounds having irregular shapes. To that end, wound dressings and surgical sponges formed from gauze and foam materials have been used for many years in surgical practice. These sponges and wound dressings have attempted to retain both the advantages of thin, soft and flexible single layer dressings and the absorptive cushioning and insulating properties of thicker pad-like structures. As a result, the sponges and wound dressings have traditionally been formed of multiple layers of thin, soft, low-count gauze material which are unified along fairly widely separated lines usually extending longitudinally or transversely.
Although such wound dressings and surgical sponges have been found useful in the past, none have provided the capability of absorbing large amounts of wound exudate without inhibiting the healing of the wound to which it is contacted. Most all of these dressings, including gauze and sponges, adhere to the wound upon removal, thereby damaging the wounds to which they are attached. This in turn prolongs the healing of such wounds. It would therefore be desirable to have a wound dressing having a structure which is thin, flexible and soft yet absorbs wound exudate in the same manner as the more thick pad-like wound dressings. Further, it would be desirable to have such a wound dressing which also has the capability of absorbing exudate, such as blood and the like, which are not readily absorbed by some hydrophilic materials.
Accordingly, there is a need in the art for a wound dressing capable of absorbing large amounts of wound exudate including blood and the like without inhibiting the healing of the wound to which it is contacted. There is also a need for such a wound dressing which has a thin, flexible and soft structure so as to permit the wound dressing to be precut, sterilized, and readily available for application to a draining wound having irregular shapes and depths. Finally, there is a need for such a wound dressing which can be removed neatly as a single piece without adhering to the new cell tissue of the wound.